FOR THE FARMER.

Manawatu Standard, Volume LX, Issue 141, 15 May 1940, Page 12

FOR THE FARMER.

INTERNAL PARASITES OF PIGS. (Written for the “Standard.”) Coccidiosis in pigs is due to the presence in the intestine of organisms known as coeeidia, “Euneria debliecki,’ and related forms. The largest of these parasites in the infective or oocyst stage arc about one five-hundredth of ail inch in diameter, and tile smallest ones arc less than half that sine. Coccidia occur in the cells lining the walls of the intestine and they undergo their growth and development within these cells. The oocysts stages of coeeidia) are discharged into the cavity of the intestine and pass out with the droppings. Before, they can infect pigs the oocysts must undergo development in .the open. Life history.—The oocysts are swallowed by pigs with feed and water that have been contaminated with the droppings of infested pigs. On reaching the intestine, the contents of the oocyst, consisting of several infective bodies, arc liberated, and each infective body is callable of penetrating and damaging a coll of the intestinal lining. Each new infective body develops at the expeuse of the cell and produces a number of new infective bodies. Each of the newlyformed infective bodies is capable of entering a neighbouring coll and repeating the process of development, multiplication, and coll destruction. The multiplication of coeeidia docs not continue indefinitely, however, and if hut i'cw oocysts are swallowed by a pig the few cells that are destroyed by the developing coeeidia may not produce serious injury. Sooner or later in the course of the development of coeeidia oocysts are formed. As already noted, the oocysts are discharged with the droppings and propagate the infection. Pigs which recover from coccidiosis may continue to discharge oocysts for a long time. Such pigs are classed as carriers as they transmit coccidiosis to susceptible pigs. Damage produced.—Tn light cases no symptoms are observed. In marked infection pigs are more or less indifferent to their surroundings, show considerable scouring, are generally unthrifty, and become emaciated. Infected pigs may become potbellied and have arched hacks. In extreme cases, which may result in death, emaciation is very pronounced, especially in the region of tiro hips. Tlic hones of the hips become rather prominent because of loss of flesh in that part of the body. These symptoms are associated with a marked destruction of intestinal cells and a swelling and congestion of the intestinal wall. There is no treatment that is known to lie effective in curing coccidiosis in pigs. Control.—The control is, however, largely a matter of sanitation. Severe cases are generally noted in pigs that have been raised under poor sanitary conditions, particularly in pigs running in old pig-yards and on low-lying and wet pastures. These conditions afford ideal surroundings for the survival of the oocysts. Marked improvement is usually noticed in infested pigs when they arc moved from their insanitary Hirroundings to clean pastures or isolated in houses having concrete floors. The removal of an infected pig from the area where the infection was acmiired reduces the chances of reinfection and affords opportunity for recovery. The recommendations for controlling the large intestinal roundworm should he followed for the control of coccidiosis and the dysentery-producing protozoa. TAPEWORMS. Tapeworms, occur in domestic animals either as adults in the intestine, as a rule, or as bladder worms located outside of the digestive tract. On casual examination there is little resemblance between a bladder worm and an adult tapeworm. Actually, however, a bladder worm is ail incompletely developed tapeworm consisting of a fully-formed head and neck. The heads of the bladder worms bear four cup-shaped suckers .and a double crown of hooks for the attachment of the future tapeworm to the wall of the intestine of the final host. The head and neck are inverted into the thin-walled bladder at one end, the arrangement resembling the tip of a glove finger that is pushed in at one end. The inverted head and neck appear as ail opaque object in the bladder, which is filled with a more or less clear fluid. If a bladder worm or part of a carcase containing one or more bladder worms is eaten by an animal capable of harbouring the adult tapeworm, the head and neck of tlie bladder worm are turned outward in the stomach, and the wall of the bladder portion of the worm is digested. Upon reaching the intestine the head becomes attached to the wall by means of its suckers and hooks, and the neck begins to .bud off segments, forming in the course of about two months a jointed, flattened, whitish worm which may attain a length of several feet. Pigs harbour throe species of bladder worms, however, one species developing into an. intestinal tapeworm in man, and the other two species developing into tapeworms in the intestine of dogs. THE POHK BLADDER WORM. This tapeworm, Taenia solium, occurs in pigs in the immature or bladder worm stage. The fully grown or adult tapeworm occurs in human beings and is known as the porlc tape-

worm. The bladder worm stage is more Jor less spherical to lemon shaped and is from a little over one-fifth to twofifths of an inch in maximum diameter. The pork bladder worm occurs in the musculature of pigs, especially in the muscles of the abdomen, the muscular portion of the diaphragm, the torn muscles, the heart, the muscles used in chewing, the tongue, the muscles between the ribs, certain muscles of the hind legs, and shoulder muscles. Pork bladder worms have been found also in the brain, eyes, liver, lungs, pancreas, spleen, and in several other locations.

Lifo history.—Should a live pork bladde'r worm be swallowed with raw o'r incompletely cooked pork by a human being, the combined action of the digestive fluid and the warmth of the human stomach causes the head and neck of the worm to be pushed out, leaving the more or less shrunken bladder behind the neck; the wall of the bladder is .digested. Upon reaching the small intestine, the parasite attaches itself to the intestinal wall by means of its suckers and hooks and develops in the course of about two months into a gravid (egg-producing) tapeworm. The tapeworm may attain a length of three to five feet, the longest points in the tail end being about half an inc-ii long and one-third of an inch wide. The joints all segments at the tail end become detached from the tapeworm chain and are expelled with the excreta, new segments taking their place by growth which occurs in the region of the neck. The detached segments expelled with the excreta contain numerous eggs which become liberated as the segments disintegrate. Pigs become infested as a result of swallowing the tapeworm eggs or entire segments, each containing hundreds of eggs. On getting into the pig’s digestive canal the eggs hatch and the young worms, which escape from the eggshells, bore into the

wall of the digestive canal, and arc carried by the blood stream, aided probably by their own migrations, to the various locations in which they arc known to occur.—To be continued.